Download BIOL 103 Chapter 4-1 for Students

The Human Body:
From Food to Fuel
BIOL 103, Chapter 4
(Part 1)
Today’s Topics
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Taste and Smell
GI Tract
Digestion and Absorption
Assisting Organs
Circulation of Nutrients
Taste and Smell: The Beginnings
of our Food Experience
• Sight, smell, thought, taste, and sound
– Can trigger a set of responses that prepare the
digestive tract to receive food
The Gastrointestinal (GI) Tract
• Organization
– ____________________
• mouth, esophagus,
stomach, small intestine,
large intestine, rectum
– ____________________
• Salivary glands, liver,
gallbladder, and pancreas
Organization of the GI Tract
• Functions:
– __________________(the receipt and softening
of food)
– __________________ of ingested food
– __________________ of digestive enzymes, acid,
mucus, and bile
– __________________ of end products of
digestion
– __________________ of undigested material
– __________________ of waste material
Organization of the GI Tract
• Structural organization of
the GI tract
– ____________________
(innermost layer)
• Glands and absorptive cells
– ____________________
______________________
• Mix and move the food
– _____________________:
valve that controls the
movement of food
material so that it travels
through the GI tract in only
one direction.
Overview of Digestion
• Mouth
– Chewing  _______________________________
– Saliva  _________________________________
• Down the GI tract:
– Physical movement
• __________________________: waves of muscular
contraction that helps push food down the GI tract
• __________________________: a periodic muscle
contractions in the small intestine that move the
content forward and backward,
Overview of Digestion
• Chemical breakdown:
– __________________________ (a mass of partially
digested food + digestive juices moving from
stomach into small intestine)
• _______________________: are proteins that catalyze
(speed up) reactions but are not altered in the process.
– Examples: amylase, lipase, etc.
• Other secretions:
Overview of Digestion
Overview of Absorption
• 3 Main processes allow nutrients to be absorbed
from GI tract  blood/circulation
– _____________________: movement of molecules
through cell membrane from ___________________
_____________________________________________
– _____________________: movement of molecules
through cell membrane from ___________________
_____________________________________________
– _____________________: movement of molecules
through cell membrane ________________________
_____________________________________________
_
Overview of Absorption
Assisting Organs
• Salivary glands
– ______________________________
– Supply enzymes
• Liver
– _______________________________________
– “Detox center:” _________________________
– “Chemical factory”: ______________________
• Produce blood proteins, cholesterol, sugar
– ____________________: stores hormones, cholesterol, minerals,
sugar, etc.
• Gallbladder
– ____________________________________
– Bile’s Enterohepatic circulation:
• _______________________________________
_________________________________________
• Pancreas
– ____________________________________
– Secretes hormones _________________________
Putting It All Together:
Digestion and Absorption
• Mouth
– Enzymes
• ____________________________________
• ____________________________________
– Saliva
• Moistens food for swallowing  forms into bolus
• Esophagus
– Transports food to stomach
– ___________________________________________
• “Heartburn”
Putting It All Together:
Digestion and Absorption
• Stomach Enzymes:
– Hydrochloric acid/gastric acid
1. ________________________
2. ________________________
1.
2.
breaks down 3D structure of protein
_________________________________________________________________
– Pepsin: _____________________________________
– Gastric lipase: some fat digestion
– Gastrin (hormone) stimulates gastric secretion and
movement
– Intrinsic factor _______________________________
Putting It All Together:
Digestion and Absorption
• Small intestine (~10ft)
– _____________________
– Sections of small intestine:
• _____________________
• _____________________
• _____________________
– Nutrient digestion
• Bicarbonate ___________
_______________________
• Pancreatic and intestinal
enzymes
– ___________________
– ___________________
– ___________________
• Vitamins, minerals,
cholesterol are not
digested and generally
absorbed unchanged.
Putting It All Together:
Digestion and Absorption
• Small intestine
– Completes absorption:
• _________________________________
___________________________________
– 600x fold increase/tennis court!
• Most nutrients absorbed here
• Fat-soluble nutrients 
______________
___________________________________
• Water-soluble nutrients  ___________
Putting It All Together:
Digestion and Absorption
• Large Intestine
– Ileocecal valve
– Sections
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_____________________
_____________________
_____________________
_____________________
– Digestion
• Peristaltic movement is
slow, taking 18-24 hours
for material to travel
• Some bacterial activity
Example:
_____________________
Beans, Beans, Beans!
• Beans are made up of oligosaccharides (e.g.
raffinose and stachyose), a component of
fiber.
• They are ignored until they are met by 700+
species of bacteria in your large intestine.
– _________________________
_____________________ _________________
Putting It All Together:
Digestion and Absorption
• Large Intestine:
– Absorption
• ___________________
• ___________________
• ___________________
– _____________ at anal
sphincter
• Feces: 60% solid (bacteria,
dietary fiber, digestive
secretions), 40% water
Circulation of Nutrients
• Vascular system: veins
and arteries
– ____________________
______________________
______________________
______________________
______________________
– Removes wastes
• ____________________
• ____________________
Circulation of Nutrients
• Lymphatic system: vessels that drain lymph
(clear fluid formed in the spaces between
cells)
1. Fat soluble-vitamins are absorbed into lymph
vessels in the intestine.
2. _______________________________________
__________________________________________
– Clean-up: proteins and large particulate matter in
tissue spaces  lymphatic system  removed
Circulation of Nutrients
• Excretion and Elimination
– Lungs
• Excrete __________________________________
– _________________________________________
• Excrete digestive wastes
– Urine: urea + salts + water
• Maintain water and ion balance